But it was what was not said at the formal swearing-in ceremony for Premier David Bartlett's new ministry that was more interesting.

National Greens deputy leader Christine Milne, there with former Tasmanian Greens leader Peg Put, said that it was a coming-of-age for her party after she watched Nick McKim sign up as Australia's first Greens government minister.

"This has been 21 years in the making," Senator Milne said.

"It was May 13, 1989, when the first Greens entered the Tasmanian Parliament. That was the start of it. This is a fitting 21st birthday present."

But the unspoken communication between the main players at yesterday's ceremony suggested that the Greens should proceed with caution rather than celebration.

Government House had done its bit to encourage the state's new Labor Greens minority government to be a co- operative model.

Braddon MHA Bryan Green, back as a senior minister responsible for six portfolios, four years after being relegated to the back bench after facing court twice, was seated next to his former arch enemy, Greens leader Nick McKim.

And Governor Peter Underwood urged the new Government to be tolerant and respectful of each other, and always work collaboratively for good government.

But he probably didn't notice the looks of glee shared between Mr Bartlett and Mr Green as Mr McKim took his oath as a new minister, swearing allegiance to the Queen and the Government.

(They looked like boys at school whose plan had worked.)

Or the heavy hand that Mr Bartlett placed on Mr McKim's shoulder when he congratulated him afterwards instead of the kisses and hugs he gave his Labor colleagues.

Or Mr Green and Mr McKim talking to everyone around them except to each other sitting together in the front row.

Or Treasurer Michael Aird studying the floor as Mr McKim was sworn in as Human Services Minister.

Mr Green said after the ceremony that it was a fantastic feeling to be part of the Government front bench again.

"I'll be far more process driven as a minister in the future. I will make sure that the decisions that I make are absolutely appropriate decisions and I will make sure that the process backs that up," he said.

Mr Aird said that he had no problem working alongside the new Greens cabinet members.

"I think that we have to understand that I've had good relationships with Nick and Cassy on a personal level over a long period of time... we will obviously have our policy differences but if you are sensible and reasonable and intelligent, you can try and manage those differences," he said.

He would not comment on how he would have responded if Bass Greens MHA Kim Booth had been part of the cabinet.